Photoluminescent materials absorb and store light energy when they are illuminated by visible light or invisible electromagnetic (EM) radiation (such as ultraviolet or infrared EM radiation) from an excitation source of illumination, and then reradiate the stored energy as visible or invisible light.
Building codes and regulations for passenger transportation systems (ships, vehicles, trains, trams, airplanes, and the like), mines, and other spaces require that exit routes be lighted continuously during occupation to permit safe egress at all times. Backup power sources such as batteries and petroleum-fueled generators are usually employed to ensure these requirements are met when normal power fails. These systems do not necessarily ensure that occupants will be able to see the way out if the normal building or passenger transportation system (e.g. in the case of a ship or airplane) when power is interrupted. For example, fire or explosions can damage a centrally located power source, related distribution and transfer systems, and fuel storage. Batteries can fail as they expire over a period of time. Effective emergency lighting systems are expensive to purchase, install and to maintain, requiring maintenance and management practices that are not always implemented. When emergency lighting systems fail, building or vessel evacuation plans are jeopardized. This can contribute to panic and loss of life, and physical and psychological injury.
Alternative and supplemental methods of emergency lighting include linear path marking systems that are designed to overcome some of the above problems. Linear path marking systems involve narrow lengths of light sources attached to the walls, floors, and/or other architectural features of evacuation routes so that, in darkness, the path to safety is clearly and visibly marked. They can include photoluminescent pigments that store energy when they are illuminated by visible or invisible (i.e. ultraviolet or infrared) external light from an excitation source of illumination and then release it as visible light, in decreasing intensity over a period of time during subsequent darkness.
Photoluminescent pigment paint has been sprayed onto durable substrate surfaces, but once the pigment is applied it often must be polished in order to meet aesthetic requirements. This results in considerable waste during this spraying and subsequent grinding process. In addition, solvents potentially including VOCs (Volatile Organic Compounds) are used in paints, and the spraying process releases significant amounts of pollutants into the environment. Further, paints have comparatively poor durability and tend to flake and scratch over time, especially in heavy use areas.
Photoluminescent pigment has been melted into channels cut into substrates, giving significant durability to the photoluminescent pigment for use in high-traffic areas (see, for example, U.S. Pat. No. 6,726,952). However, this requires special processing of said substrate with specific grooves or channels cut into the surface, therefore limiting the application of this process. In particular, this process cannot be applied to three-dimensional articles such as doorknobs, door closers, and the like.
In some cases, translucent tapes, paints, or add-on polymers or plastics may be applied to existing articles with photoluminescent properties in order to add some advantageous qualities such as non-slip surfaces. However, not only do the surface additions negatively impact the luminescence of the photoluminescent layer, but the new layers tend to peel and flake and in general do not have good durability, especially for such high use applications such as hand rails or stair nosings. Furthermore, application of such tapes, paints, etc., to surfaces generally takes place on-site as opposed to during the manufacture of, for example, door handles and door push bars. Due to additional labor costs and inconvenience of on-site application it would be advantageous if photoluminescent properties could be applied to articles during the manufacturing process.
Especially in the case of door hardware, including but not limited to door knobs, handles, push bars, exit devices, door closers, frames, key card devices, keys, key cards, locks, and the door itself, there is no means of delivering high-quality photoluminescent product with other advantageous qualities that is ready for direct installation without further work at the time of installation. Currently a door or related door hardware would be installed then the photoluminescence added by tapes, paints, signs, or sometimes plastics. This adds time and expense to installing a door or door hardware with luminescence in low-lighting or emergency situations.
Further, US and international standards require that doors both be clearly marked for emergency and be able to withstand both fire and high heat. For example, doors must pass heat and fire exposure requirements of industry standards organizations such as UL (Underwriters Laboratories Inc.) in the United States. In the case of the United States, doors must withstand the tests in such standards as UL 10B “Standard for Fire Tests of Door Assemblies”, and 10C “Standard for Positive Pressure Fire Tests of Door Assemblies”.
There are further examples of prior art of building materials such as tiles or carpeting having photoluminescent qualities, and such photoluminescent materials may be used in original installation of a building. However, should these building materials become damaged or require retrofitting the process is extremely expensive since the entire section of the building material must be replaced. There are few effective mechanisms by which items may be retrofitted with high-quality photoluminescent product with further advantage of heat resistance or non-slip surfaces.
There exists no effective process in the prior art for applying durable photoluminescent coatings that meet both environmental and aesthetic requirements. Furthermore, there exists no process for applying such photoluminescent coatings that have additional desirable characteristics, such as antimicrobial characteristics, heat resistance, etc. Finally, there are no examples in the prior art for cost-effective retrofitting to add photoluminescence to existing installations as new laws requiring emergency lighting come into effect both in the United States and internationally.
Accordingly, it is the object of the present invention to provide a mechanism by which photoluminescent pigment is applied to a substrate. It is a further object of the present invention to provide means for applying photoluminescent coatings that overcomes the waste, durability, and pollution problems associated with prior art methods. It is a further object of the present invention to provided means for applying photoluminescent qualities to a broad range of two- and three-dimensional substrates. It is yet a further object of the present invention to provide means for making photoluminescent coated products that have both high aesthetic value and considerably higher durability than prior art surface applications such as tape, paint, or add-on plastics or polymers. It is an object of the present invention to provide means to apply, in addition to photoluminescent coating layers to substrates, additional layers having qualities such as, but not limited, antimicrobial properties or heat resistance. A further object of this invention is to provide cost-effective photoluminescent retrofitting with other advantageous qualities. In the case of doors, an object of this invention is to provide well-lit door and related hardware for emergency or low-light situations that pass a variety of fire and heat certifications.